China National Petroleum Corporation (CNPC) is China’s largest oil and gas pipeline contractor and operator, with gas pipeline networks covering 29 provinces, municipalities and autonomous regions. Its natural gas pipelines span 50,836 km and constitute 78 per cent of the country’s total gas pipeline network. CNPC’s expanding upstream and downstream operations and greater international role has made the deployment of technology essential for addressing bottlenecks in the gas pipeline industry. In this regard, the com-pany has made some key innovations.
Apart from reducing fuel consumption, the optimisation of gas transmission systems also results in improved pipeline operations. Therefore, the use of modern gas appliances and consistent innovations in gas pipelines has economic as well as environmental benefits.
Oil and gas pipelines usually traverse long distances through remote and environmentally sensitive areas to transport large quantities of oil and gas over land and below the sea from offshore facilities. In order to ensure safety and avoid catastrophic failures, CNPC has developed unique technologies independently in five series to provide different solutions and services for the oil and gas pipeline industry. The following is a detailed explanation of these technologies, which have proved to be a success for the company.
Oil and gas transportation and storage technology
CNPC has mature technologies in the areas of oil and gas pipeline flow assurance, simulation and optimisation that facilitate pipeline planning, design, commissioning, operations as well as maintenance.
Pipeline flow assurance technology: This is deployed to predict the flow variation of oil and gas in a pipeline and evaluate flow safety. Apart from simulation, flow assurance also provides integrated solutions for the effective handling of many solid deposits like wax, gas hydrates and naphthenates. These solid deposits can interact with each other and lead to the formation of catastrophic blockages in pipelines and flow assurance failures.
Pipeline simulation and optimisation technol-ogy: CNPC’s oil and gas pipeline simulation system helps analyse, establish and optimise pipeline operation plans. This technology has been successfully used in the design and operations management of over 20 oil and gas pipelines in China. It predicts and reproduces the running and control processes of oil and gas pipeline systems.
Pipeline integrity technology
CNPC’s advanced oil and gas pipeline integrity technology provides solutions for the proper execution of a pipeline system’s functions, with a special emphasis on effective risk management.
Pipeline integrity management system (PIMS): Through the establishment of an applicable integrity management document system, database and management platform, PIMS ensures the cyclical execution of steps involving data acquisition, high consequence identification, risk assessment, integrity evaluation, repair and maintenance, and efficiency evaluation. The system keeps pipeline risks within a reasonable and acceptable limit.
Early warning and leakage detection technology for pipeline safety: Implemented in 2003, this technology has been successful in providing early warnings and accurately detecting pipeline threats and leak events. In case of corrosive cracking and geological hazards that threaten pipeline safety, CNPC has developed a distributed optical fibre compound early warning system, a pipeline acoustic wave early warning system, a geological hazard early warning system, and a pipeline leakage testing and positioning system. These systems provide graded systematic safety protection solutions for different zones of the trunk lines, accident-prone zones and major protection zones of long-distance pipelines.
Pipeline geological hazard risk management system: CNPC comprehensively utilises 3S technology – global positioning system (GPS) technology, geographic information system (GIS) technology, and remote sensing (RS) – in order to guarantee the effective execution of the geological hazard risk management system. GPS is widely used for locating pipeline characters, detecting pipeline movement, and collecting geospatial data. Environmental analyses, hazard analyses, integrity data visualisation, and the management of pipeline geospatial data are under the purview of GIS, while RS is used for monitoring geological hazards threatening pipeline safety, monitoring pipeline leakage, and evaluating environmental impact. The pipeline geological hazard risk management system, in combination with 3S technology, is used for data management and risk assessment, rapidly identifying geological hazard risks in different zones along the pipeline, and providing solutions for controlling them.
Testing, maintenance and emergency repair technology
This includes pipeline testing, defect examin-ation and emergency repairs for ensuring the integrity of pipeline structures.
Internal pipeline testing technology: This involves the utilisation of different kinds of testing equipment to detect existing or potential damage in a pipeline. With this, CNPC can carry out the internal testing of magnetic leakage corrosion, pipeline deformation and pipeline pigging, as well as testing and evaluation of the external coating of buried pipelines and the buried depth of an underwater pipeline.
Pipeline defect examination and evaluation technology: With the use of non-destructive testing instruments and a corresponding evaluation method to guarantee the integrity of pipeline structures, CNPC has successfully implemented pipeline defect examination and evaluation technology for testing several trunk pipelines and pipelines at oil and gas transmission stations in China. It has testing equipment like internationally advanced ultrasonic guided waves and phased arrays that provide the location of pipeline defects along with their qualitative and quantitative analyses. The residual strength and life of defective pipelines can be evaluated, too.
Pipeline emergency repair technology: This focuses on the planned maintenance and reconstruction of oil and gas pipelines, emergency salvage in case of any incident (emergency re-pair under pressure), replacement of corroded pipe sections, and reconstruction of offtake stations, among others. CNPC provides online pipeline maintenance and emergency repair services like tapping, plugging, replacements and remedies for various pipe diameters.
Equipment and production
Advanced pipeline equipment and systems facilitate leakage detection and subsequent recovery, and have the added advantage of timely alarms and rapid response.
Distributed optical fibre compound early warning system: This involves the synthetic utilisation of optical fibre early warning technology and sound oscillation early warning technology. It makes breakthroughs on the basis of early warning advance times and signal identification accuracy, thus resolving the bottleneck of traditional distri-buted optical fibre early warning techniques.
Pipeline acoustic wave early warning system: This has been suitably deployed for implementing real-time alarms and locating events threatening pipeline safety, such as the destruction of anti-corrosive pipeline coating, knocking, boring and illegal excavation. This has an alarm accuracy rating within a protective zone of more than 95 per cent, while the false alarm rating is less than 1 per cent.
Pipeline leak testing and positioning system: Based on sound wave and suction wave sensing technologies, this system has the ability to accurately locate any tiny leaks along the pipeline and send out alarms. It also has the advantage of being simple to install and arrange.
Pipeline leakage control and recovery machine: This machine is suitable for salvaging high-pressure pipeline leaks. With its high recovery efficiency, the leaked fluid can be recovered with high leak pressure.
Design and construction technologies
For pipeline design, CNPC selects an optimal piping route through technologies like GIS, and then conducts analyses and calculations on the transmission technology. Subsequently, it prepares construction drawings, feasibility studies and reasonable pipeline route survey designs.
CNPC has the largest anti-corrosion processing and production line in Asia. Its hot-bent elbow anti-corrosion operating line, which is the world’s most advanced technology in this area, enables the anti-corrosion operation of elbow exteriors in different diameters, angles and forms. Apart from this, the company also employs different welding methods depending on conditions and processes, while also using horizontal directional drilling, shield and pipe-jacking in its pipeline crossing technology.
Conclusion
CNPC has proven expertise in oil and gas field surface construction, long distance pipeline construction, and marine engineering and construction. It is supported by well-established quality management systems and operational and technical procedures. The company’s second West-East Gas Pipeline project is one of China’s most complicated gas pipeline projects as it has pipelines traversing difficult geological landforms. With efforts channelised towards the integration of pipeline management and the effective deployment of pipeline engineering construction technologies, CNPC is aiming to serve the global oil and gas transmission segment with the utmost safety and highest efficiency. N